Apparatus for preheating fine granular material

ABSTRACT

A plurality of eddy chambers of the cyclone separator type are arranged in superimposed levels through which the material passes downward in series and through which the hot gases travel upward in series. Each eddy chamber in at least the uppermost level is provided with a dip pipe, and each eddy chamber in at least the lowermost level is constructed without any dip pipe.

United States Patent Polysius et al.

[151 3,656,722 [451 Apr. 18, 1972 [54] APPARATUS FOR PREHEATING FINEGRANULAR MATERIAL [72] Inventors: Jochen Polysius; Horst Ritzrnann, bothof Neubeckum, Germany [73} Assignee: Polysius AG, Neubeckum, Germany[22] Filed: May 28, 1970 [2 l] Appl. No.: 41,286 [30] ForeignApplication Priority Data Aug. 12, 1969 Germany ..P 19 41 071.0 [52] US.Cl. ..263/21 A, 34/57 R [51] Int. Cl ....F27b 15/00, F26b 17/00 [58]Field of Search ..263/32 R, 21 A; 34/57 R [56] References Cited UNITEDSTATES PATENTS 3,364,583 1/1968 Friedrich ..263/32 3,317,201 5/1967Muller et al. ..263/32 3,452,968 7/1969 Shimizu et al ..263/32 X PrimaryExaminer-John J. Camby Attorney-Marshall & Yeasting [5 7] ABSTRACT Aplurality of eddy chambers of the cyclone separator type are arranged insuperimposed levels through which the material passes downward in seriesand through which the hot gases travel upward in series. Each eddychamber in at least the uppennost level is provided with a dip pipe, andeach eddy chamber in at least the lowermost level is constructed withoutany dip pipe.

4 Claims, 1 Drawing Figure BACKGROUND OF THE INVENTION The inventionrelates to an apparatus for the preheating of fine granular material bymeans of hot gases, consisting of a plurality of eddy chambers of thecyclone type arranged at several superimposed levels, wherein the hotgas stream which is distributed to the eddy chambers of the first,lowermost stage is reunited in a central eddy chamber of the secondstage, before it is again distributed to the eddy chambers of the thirdstage, while the divided stream of material coming from the eddychambers of the third stage is united in the central eddy chamber of thesecond stage, before it is again distributed to the eddy chambers of thefirst stage.

In the known preheaters of this type the eddy chambers are in the formof cyclone separators which are provided as usual with dip pipes. Inpractice it is found, however, that particulady in the high temperaturezone of the preheater, i.e. in the lowermost stage, the dip pipes of thecyclone separators are subjected to extraordinarily severe thermal andmechanical deterioration. In many cases, the dip pipes of the lowermostcyclone separators are already burned out after a relatively shortperiod of operation, and this has necessitated difficult repairsheretofore, which often bring about lengthy shutdowns of the entireinstallation.

SUMMARY OF THE INVENTION The object of the invention accordingly is toconstruct an apparatus of the type which has been described in such amanner that the difficulty which has been mentioned is eliminated.

In accordance with the invention, this object is achieved by providingthe cyclone-type eddy chambers with dip pipes in at least one stage, andby constructing the eddy chambers without dip pipes in at least onestage lying in a zone of higher gas temperature.

When the dip pipes are eliminated, particularly in the lowermost stagesof the preheater which are subjected to the highest gas temperature, anundesirable and hazardous source of trouble is thereby eliminated. Asshown by tests, the omission of the dip pipes impairs onlyinsignificantly the separating capacity in the cyclone separators inquestion. Moreover, in the lower stages of the preheater a somewhatprolonged dwell time of the material in the hot gas stream is even verydesirable for an intensive exchange of heat in most cases. The retentionof the dip pipes in the less intensively heated stages of the preheater,particularly in the uppermost stage of the preheater, guarantees on theother hand the complete separation of the material from the gas streamleaving the preheater.

Accordingly, in the practice of the invention there is achieved asubstantial improvement in reliability of operation and freedom fromshutdowns of the installation, with simultaneous preservation of a goodrate of heat transfer and a complete separation of dust from the gasstream leaving the preheater.

In accordance with a practical embodiment of the invention, in at leastone stage the material discharge ducts of the eddy chambers are providedwith shutoff devices, and in at least one of the stages which lie in azone of higher gas temperature the material discharge ducts of the eddychambers are constructed without shutoff devices.

Like the dip pipes, the shutoff devices which are ordinarily provided inthe material discharge ducts are subject to a substantial mechanical andthermal deterioration. This undesirable source of trouble is likewiseeliminated by omission of the shutoff devices in the hottest stages ofthe preheater. The retention of these shutoff devices in at least onecooler stage of the preheater, preferably in the uppermost stage,guarantees on the other hand, in conjunction with the retention of thedip pipes in these stages, the good separating capacity which isnecessary for a complete separation of dust from the gas stream.

The open cross section of the material discharge ducts which areconstructed without shutoff devices is advantageously made at leastgreat enough so that a maximum of percent, preferably a maximum of 50percent of the cross section is occupied by material, and at the mostgreat enough so that in total a maximum of 10 percent, preferably amaximum of 5 percent of the entire gas stream passes through thematerial discharge ducts of this stage.

BRIEF DESCRIPTION OF THE DRAWING The drawing is a schematic longitudinalsection of a preferred form of apparatus embodying the inventionDESCRIPTION OF THE PREFERRED EMBODIMENT The illustrated apparatus servesfor the preheating of fine granular material, which is finally suppliedto a rotary kiln l. The preheater comprises several eddy chambersarranged in superimposed levels, which are constructed like cycloneseparators, and are referred to hereinafter as cyclone separators forthe sake of simplicity. The lowermost stage of the preheater consists ofthe cyclone separators 2, 2, the second stage consists of one centralcyclone separator 3, the third stage consists of two cyclone separators4, 4' and the fourth stage consists of two cyclone separators 5, 5.

These cyclone separators are connected by means of their gas andmaterial ducts as follows: the gas duct 6 coming from the rotary kiln lis divided and leads to both of the cyclone separators 2, and 2. Theirgas discharge ducts 7, 7' both discharge into the central cycloneseparator 3, and preferably are tangential in the same sense ofrotation. The gas discharge duct 8 of the cyclone separator 3 is dividedand leads to the cyclone separators 4 and 4', which are connected bymeans of 7 their gas discharge pipes 9, 9' with the cyclone separators5, 5'. The gas discharge ducts l0, 10 of the latter cyclone separatorsare connected to a common blower 11.

The material discharge ducts l2, 12 of the cyclone separators 5, 5discharge into the gas duct 8. The material discharge ducts 13, 13' ofthe cyclone separators 4, 4' are connected to the gas ducts 7, 7, whilethe material discharge 14 of the cyclone separator 3 discharges into theupper end of the gas duct 6. The material discharge ducts 15, 15 of thetwo lowermost cyclone separators are directly connected with the rotarykiln 1 or with its inlet housing.

While the material discharge ducts l2, l2 and 13, 13+ of the twouppermost stages of the preheater are provided with shutoff devices 12a,l2'a, 13a, 13'a, for example in the form of balanced dampers,suchdevices are lacking in the material discharge ducts 14, 15 and 15'of the two lower preheater stages. Both cyclone separators 2, 2' of thelowermost preheater stages furthermore are constructed without dippipes, while all of the other cyclone separators 3, 4, 4', 5, 5' areprovided with the usual dip pipes 3a, 4a, 4a, 5a, and 5'a.

The path of flow of the hot gases coming from the rotary kiln 1 isindicated by arrows 17; the hot gas stream is distributed first to thetwo cyclone separators 2, 2', is then reunited in the central cycloneseparator 3, is distributed anew to the cyclone separators 4, 4 thenpasses through the cyclone separators 5, 5' and is finally withdrawnthrough the blower 1 1.

The countercurrent path of the material being preheated is marked by thearrows 18: the material entering the gas ducts 9, 9' is separated in thecyclone separators 5, 5, then travels into the gas duct 8, is led to thecyclone separators 4, 4, travels after separation in these cycloneseparators into the gas ducts 7, 7 is brought together anew in thecentral cyclone separator 3 and is once more distributed, after enteringthe gas duct 6, to the two cyclone separators 2, 2', before it travels,highly preheated, into the rotary kiln 1.

We claim:

1. Apparatus for preheating fine granular material by means of hotgases, comprising a plurality of eddy chambers of the cyclone separatortype, arranged in superimposed levels through which the material passesdownward in series and through which the hot gases travel upward inseries, each eddy chamber of the cyclone separator type having a lateralgas inlet which is located adjacent to the top of the eddy chamber andwhich is directed to cause the entering gas to eddy in cy'clonefashionso as to separate solids from the gas by centrifugal force, and eacheddy chamber also having a lower portion that tapers downward to abottom outlet for discharging separated solids, wherein the improvementcomprises a central vertical gas outlet duct at the top of each eddychamber, the lower end of such outlet duct of each eddy chamber in atleast the uppermost level being extended downward into the eddy chamberin order to improve the separation of solids, and the lower end of thegas outlet duct of each eddy chamber in at least the lowermost levelterminating flush with the top of the eddy chamber in order to protectthe duct from thermal deterioration.

2. Apparatus according to claim 1 wherein the eddy chambers are arrangedin at least three superimposed levels, the lower end of the centralvertical gas outlet duct of each eddy chamber above the lowermost levelbeing extended downward into the eddy chamber. 7

3. Apparatus according to claim 1 wherein the eddy chambers are arrangedin at least three superimposed levels, the first and third levels fromthe bottom each comprising two eddy chambers, and the second level fromthe bottom comprising only one eddy chamber having two gas inlet ducts,which lead from the two eddy chambers of the first level and into eachof which discharges a material supply duct leading from one of the eddychambers of the third level.

4. Apparatus according to claim 3 wherein a fourth level from the bottomcomprises two eddy chambers each of which has a gas inlet duct leadingfrom one of the eddy chambers of the third level, the latter eddychambers being connected to a gas inlet duct, which leads from the eddychamber of the second level and into which discharge two material supplyducts leading from the eddy chambers of the fourth level, each of suchmaterial supply ducts being providedwith a shutoff device.

1. Apparatus for preheating fine granular material by means of hotgases, comprising a plurality of eddy chambers of the cyclone separatortype, arranged in superimposed levels through which the material passesdownward in series and through which the hot gases travel upward inseries, each eddy chamber of the cyclone separator type having a lateralgas inlet which is located adjacent to the top of the eddy chamber andwhich is directed to cause the entering gas to eddy in cyclone fashionso as to separate solids from the gas by centrifugal force, and eacheddy chamber also having a lower portion that tapers downward to abottom outlet for discharging separated solids, wherein the improvementcomprises a central vertical gas outlet duct at the top of each eddychamber, the lower end of such outlet duct of each eddy chamber in atleast the uppermost level being extended downward into the eddy chamberin order to improve the separation of solids, and the lower end of thegas outlet duct of each eddy chamber in at least the lowermost levelterminating flush with the top of the eddy chamber in order to protectthe duct from thermal deterioration.
 2. Apparatus according to claim 1wherein the eddy chambers are arranged in at least three superimposedlevels, the lower end of the central vertical gas outlet duct of eacheddy chamber above the lowermost level being extended downward into theeddy chamber.
 3. Apparatus according to claim 1 wherein the eddychambers are arranged in at least three superimposed levels, the firstand third levels from the bottom each comprising two eddy chambers, andthe second level from the bottom comprising only one eddy chamber havingtwo gas inlet ducts, which lead from the two eddy chambers of the firstlevel and into each of which discharges a material supply duct leadingfrom one of the eddy chambers of the third level.
 4. Apparatus accordingto claim 3 wherein a fourth level from the bottom comprises two eddychambers each of which has a gas inlet duct leading from one of the eddychambers of the third level, the latter eddy chambers being connected toa gas inlet duct, which leads from the eddy chamber of the second leveland into which discharge two material supply ducts leading from the eddychambers of the fourth level, each of such material supply ducts beingprovided with a shutoff device.